#include <stdlib.h>
#include <stdio.h>
#include "stack2.h"

int getop(Stack* s, int& n1, int& n2)
{
	if (s->empty())
	{
		printf("empty stack!\n");
		return 0;
	}
	n2 = s->pop();
	if (s->empty())
	{
		s->push(n2);
		printf("two operands needed!\n");
		return 0;
	}
	n1 = s->pop();
	return 1;
}

int main(void)
{
	Stack* s = createStack();
	while (1)
	{
		char str[31];
		int n;
		printf("> ");
		gets(str);
		if (sscanf(str, " %d", &n)==1) s->push(n);
		else
		{
			int n1, n2;
			char c;
			sscanf(str, "%c", &c);
			switch(c)
			{
				case '+':
					if (getop(s, n1, n2)) s->push(n1+n2);
					break;
				case '-':
					if (getop(s, n1, n2)) s->push(n1-n2);
					break;
				case '/':
					if (getop(s, n1, n2)) s->push(n1/n2);
					break;
				case '*':
					if (getop(s, n1, n2)) s->push(n1*n2);
					break;
				case 'q':
					return 0;
				default:
					printf("error\n");
			}
		}
		for (int i=0; i<s->top; i++)
			printf("%d:%6d\n", i, s->elems[i]);
	}
}